In the case of arrangements having a circuit carrier and electrically conductive pins, so-called “whisker growth” can occur at contact sites between the circuit carrier and the electrically conductive pins, wherein a metallic crystal structure (so-called “whisker” or “hair crystal”) is formed. The whiskers are, in particular, pin-shaped monocrystals. By way of example, tin and zinc are particularly prone to whisker growth of this type. The reasons why whiskers are produced are not completely known. It is, however, assumed that the process is triggered by thermo-mechanical stresses in the surface material of the pins as a result of mechanical deformation, electro-physical mechanisms between the substrate of the circuit carrier and the surface material of the pins, and/or intrinsic stresses in the metal of the pins as a result of intensive contact or diffusion stresses with the substrate material of the circuit carrier. Whiskers can grow at a rate of a few micrometers per year up to a millimeter per year and have a typical diameter of a few micrometers.
Whiskers can produce undesired electrical connections—by way of example, between high ohmically separated potentials of an electronic circuit that is arranged on the circuit carrier. This can cause the falsification of signals. Moreover, it is possible, in the case of a high electrical potential difference or as a result of high currents at a potential when closing a field contact, for an arc to occur temporarily as a result of the vaporization of the whiskers. This can cause electronic components on the circuit carrier to become damaged as a result of a short-term overcurrent or a short-term overvoltage. Moreover, whiskers can break off as a result of a mechanical shock and in other circuit regions of the circuit carrier remote from their growth region said whiskers can lead to negative influences on the circuit carrier, by way of example, short circuits.
In order to avoid or reduce the growth of whiskers, it is known to provide surface alloys on pins using alloy additives, such as, for example, silver or gold. However, this variant is very cost intensive owing to the high material value of these metals.